Switch-over contact arrangement for power relays

ABSTRACT

A low profile power relay contact is made possible by an assembly comprising a bifurcated contact spring having one shank bent above a level of the spring and overlapping an unbent shank whereby the bifurcated portions securely grip but do not impart rotative forces to an operating member which is moved up and down in response to movement of an armature by an electromagnetic field. A first carrier plate lies in generally the same plane as the unbent portion of the contact spring and is below the bent contact spring while a second carrier plate is bent to lie above the unbent carrier spring whereby upon movement of the operating member a contact is made and a contact is broken.

United States Patent [72] Inventors HerbertKrautwald;

Helmut Moller; Richard Siepmann, Munich, Germany [21] Appl. No. 799,785

[22] Filed Feb. 17, 1969 [45] Patented May 4, 1971 [73] Assignee Siemens Aktiengesellschaft Berlin and Munich, Germany [32] Priority Feb. 19, 1968 [3 3 Switzerland [54] SWITCH-OVER CONTACT ARRANGEMENT FOR POWER RELAYS 10 Claims, 5 Drawing Figs.

[52] US. Cl 335/185, 335/196, 200/166 [51] Int. Cl H0lh 1/12 [50] Field of Search 335/185,

Bba v1 [56] 7 References Cited UNITED STATES PATENTS 1,721,012 7/1929 Fagan 337/340 FOREIGN PATENTS 620,788 12/1959 ltaly 200/166(B8) Primary ExaminerHar0ld Broome Attorney-Hill, Sherman, Meroni, Gross and Simpson ABSTRACT: A low profile power relay contact is made possible by an assembly comprising a bifurcated contact spring having one shank bent above a level of the spring and overlapping an unbent shank whereby the bifurcated portions securely grip but do not impart rotative forces to an operating member which is moved up and down in response to movement of an armature by an electromagnetic field. A first carrier plate lies in generally the same plane as the unbent portion of the contact spring and is below the bent contact spring while a second carrier plate is bent to lie above the unbent carrier spring whereby upon movement of the operating member a contact is made and a contact is broken.

will

SWITCH-OVER CONTACT ARRANGEMENT FOR POWER RELAYS BACKGROUND OF THE INVENTION cal viewpoint, firmly established. Likewise, the contact spacings which are necessary in actual practice to provide voltage stability may not go below a certain minimum measurement. With these design factors substantially fixed it has heretofore not been possible in power relays to reduce the relay height below that permitted by these relatively fixed dimensions.

Because of the great press for the miniaturization of electrical and electronic components the power relays constructed according to the prior art have in effect become too large with respect to the other components whereby a great need has arisen for their reduction in size. Moreover, the increasing cost and complexity of electrical systems and their increasing costs of manufacture have made efficiency of design and manufacture a highly critical factor in their use.

SUMMARY OF THE INVENTION The disadvantages of the prior art are overcome by the very 'efficient, convenient and economic structure of the present invention wherein a low profile switch-over contact arrangement. for power relays comprises a contact spring of a generally planar configuration having a first end bifurcated to provide juxtaposed first and second spring leg portions each having one end connected to said contact spring and a free end portion with contact means thereon. The first leg has its free end portion bent out of the plane of the contact spring while the second leg remains generally in the plane of the contact spring. First arid second carrier plates electrically insulated from said contact spring have an anchored end and a contact means carrying end with the means carrying the end of the first carrier plate lying below said first spring leg and the second carrier plate having its contact means carrying end bent out of the plane of the remainder of the second carrier plate and lying above the second spring leg portion. We have found that by bending the portions of the legs and carrier plates we may place the contact springs and first and second carrier plates generally in the same plane and thereby assure a minimum overall height and a low profile.

A power relay plug-in base supports the contact spring, the carrier plate, an electromagnetic coil, a yoke, a yoke support, an armature stop and suitable connector prongs. A protective cover may be attached to the body by suitable means such as a clip. ln practice we have found it advantageous to make the body member of a one-piece molded construction and to anchor the contact spring and the inner ends of the carrier plates directly into the body.

The free ends of the first and second leg portions are biased toward each other and securely grip the base portion of a U- shaped operating member which passes below the free end portion of the first leg and above the free end portion of the second leg. It is an important feature of this invention that the free end portions of the spring legs have laterally projecting portions which extend towards each other in their respective planes so that the laterally projecting portion of the first leg lies above the laterally projecting portion of the second leg. By means of this construction the rotative forces which would be applied to the operating arm by the spring legs are substantially diminished.

Upstanding arms at each end of the base portion pass' through holes in the base portion of a U-shaped armature. ln the illustrated embodiment the U-shaped armature partially encircles one end of an electromagnetic coil with the free ends of the armature arms being connected to a spring-biasing means which acts to pivot the armature about the arm free ends and bias the armature base end upwardly against a stop member. The armature base end is also biased upwardly by the second leg of the contact-spring working through the operating arm. In this position the second spring leg free end portion contacts the bent portion of the second carrier plate to make electrical contact whereas the first spring leg free end portion will not be contacting the first carrier-plate portion. When the coil is energized the electromagnetic field will drive the base portion of the armature toward the yoke and thus move the operating member downwardly in a direction generally perpendicular to the contact spring and the carrier plate whereby the second contact is broken and the first contact between the first spring leg portion and the first carrier plate is made.

The free end portion of the first spring leg has a hole therethrough which receives an upstanding projection on the operating member. In this very simple manner the operating member is held in position between the spring legs.

From the above brief summary the advantages of the present invention over the prior art may be clearly seen. Many other advantages, features and additional objects of the present invention will become manifest to those versed in the art upon making reference to the detail description and the accompanying sheets of drawings in which preferred structural embodiments incorporating the principles of the present invention are shown by way of illustrative example.

BRIEF DESCRlPTlON OF THE DRAWlNGS F IG. 1 is an elevational side view with parts in cross section and with the side portion of the cover removed to illustrate a low profile power relay device embodying the present invention;

FIG. 2 is an elevational end view as the structure of FIG. 1 would be seen in a section along the lines ll-ll;

HO. 3 is an enlarged perspective view of the details of the contact arrangement with parts broken away;

FlG. 3a is plan view of just the bifurcated end portion of the contact spring illustrating the overlap of the portions thereof;

FIG. 3b is an end elevational view of the structure of FIG. 30 again illustrating the overlap portions of the contact spring legs.

DESCRlPTlON OF THE PREFERRED EMBODlMENT Referring to FIG. 1 the low profile construction embodying the present invention may be clearly seen. A body 1 may be molded of insulating material and may be attached to a plug-inbase B to support the component elements of the power relay.

In practice we have found it convenient to mold the body 1 integrally with the base B-so that insulating and structural integrity is assured. Moreover, this integral construction provides greater manufacturing and assembly economies. A protective cover A may be attached to the body 1 by any convenient means such as for example a clip 1a. Other body portions which may be separately or integrally formed include an armature stop 1b and a yoke support 1c as will hereinafter be described in greater detail.

A first carrier platela may be best seen in FIG. 3 where it is shown projecting from the molded insulating body 1.Th'e first carrier plate is of an L-shaped configuration having a first end Zaa anchored in the insulating body 1 and a second end 2ab projecting inwardly generally toward a centerline of the body and supporting a contact means 3 on its upper surface. A second carrier plate 2b also may be generally L-shaped having a first end 2ba anchored in the insulating body 1 and second end 2bb being bent out of the plane of the remainder for the second carrier plate 2b and carrying a contact means 4 on its lower surface. The distance which the second carrier plate portion Zbb is bent out of the plane of the remainder of the plate 2b is represented by the reference symbol a as shown in FIG. 3 Each of the anchored ends of -the carrier plates is suitably connected into the electrical circuits in which the power relay operates.

-A contact spring member 5 is supported in a usual manner on the body 1 and has its free end bifurcated by means of a slot in the free end to provide juxtaposed first spring leg portion 5a and second spring leg portion 5b. The first spring leg portion 5a has a free end portion 5ab bent out of the plane of the contact spring 5 by means of portion Saa. A contact means 6 is provided in the undersurface of the free end portion Sub. A laterally projecting portion Sac is integral with the free end portion Sab and extends towards and over a similar portion of the second contact spring leg 5b. The second contact spring leg portion 512 is generally in the plane of the contact spring 5 and has an outer free end Sba from which there extends a laterally projecting portion Sbb. The portion 5bb underlies the laterally extending portion Sac. A contact means. 7 is supported on the leg 5b at a position below the contact means 4 on the second carrier plate.

' An examination of FIGS. 3a and 3b clearly shows the overlapping of the laterally projecting portions Sac and Sbb. A distance b represents the overlap which will vary in individual constructions depending on the differences in forces f and f in the spring legs 5a and 5b, respectively. In the area of overlap these forces operate against one another and are thereby substantially neutralized. The portion Sbb may extend a distance equal to or less than the width of a slot 50 and the length of portion Saa may be greater than the length of Sac or Sbb so that the portions Sac and Sbb may be integrally formed without waste of any spring material.

An operating member 8 having a U-shaped configuration when seen in elevation has a base portion 8a underlying the first contact spring leg free end portion 5ab laterally projecting portion Sac and overlying the free end portion Sba and laterally extending portion Sbb of the spring leg 5b. The first spring leg free end portion Sab has a hole Sad therethrough which receives therethrough a projection 8d upstanding from the base portion of the operating member 8. The first and second legs 5a 5b are biased in a vertical direction towards one another so that their free ends hold the operating member base 80 in a pincerlike manner to grip it securely against movement. By means of the overlapping construction the rotative forces of the legs 50 and 5b which would tend to rotate the operating member 8 in a counterclockwise manner because of the spring bias of the legs is counteracted and substantially diminished to the point where it has no effect on the operation of the power relay. As may be seen in FIG. 2 a cutout portion Baa acts to further limit any lateral movement of the first leg or the operating member 8. A second cutout Sab is provided to allow access to the second contact shown by contact means 4and 7.

Upstanding arms 8b and Be at each end of the base portion 8a pass through holes 9b and 90 respectively in the base portion 90 of the a U-shaped armature 9. widened portions 8bb and 8cb are provided in support of the operating member for the armature. Arms 9d and 9e extend from each end of the armature base 9a to partially encircle one end of an electromagnetic coil 11. The free ends of the armature arms 9d and 9e are connected to a spring-biasing means 9f which acts to pivot the armature about the arm free ends and bias the armature base end upwardly against the stop member lb. in practice we have found a prestressed bearing spring 9f attached at one end to the free end of the armature end 9e and connected at the other end to a yoke 10 by a means 9g to provide excellent service and convenience of manufacture. A similar spring-biasing means (not shown) is provided for the other armature arm 9d.

' The armature base end is also biased upwardly by the second leg 5b of the contact spring 5 working through the operating am 8. The yoke 10 is centrally positioned with respect to the coil 11 by the body 1 in the forward yoke support its.

OPERATION Further advantageous features will be readily evident from a brief discussion of the operation of the power relay constructed according to the present invention. In a rest position as may be seen in PK]. 2 the coil 11 is not energized and the force in the second spring leg 5b together with the force in the bearing spring 9f bias the operating member 8 and the associated armature 9 upwardly against the armature stop member lb. In this position the second spring leg free end portion 5ba with its associated contact means 7 rests against the contact 4 of the second carrier plate 2b. Contact means 4 and 7 complete what might be termed the second contact.

When the coil 11 is energized the accompanying magnetic field is concentrated in the soft iron yoke 10 which in turn pulls the armature 9 into contact therewith to overcome the force in the contact spring leg 5!) and the bearing spring 9]. When the armature 9 pivots about the free end of the arms 9d and 9e it moves the operating arm 8 downwardly and this in turn pushes the spring leg 5!) in its contact means 7 away from the contact means 4!- to break the second contact. At the same time as the operating arm 8 moves down, the spring force in the free end portion Sab of the spring leg 5 moves the contact means 6 secured thereto into contacting engagement with the contact means 3 on the first carrier plate 2a so that the first contact is made. Since the switch-over contact spring 5 lies operatively on voltage with its two spring legs 5a and 5b, there arises in their operative deflection, an electrical switch-over of the currents.

An important structural advantage attained by the bifurcation of the contact spring 5 is that a greater spring force may be provided in the first spring leg than in the second. Whereas the spring constants in known contact-spring sets are equal, this is not the case in the contact arrangement according to the invention because of the bending of one of the spring legs. Thus, the bend allows a specified spring force represented by f to be imparted to the first leg whereas the second leg will carry the spring force of the contact spring 5.

From the above-noted summary and description of our invention it may be seen that we have provided a convenient, efficient and extremely economical compact power relay device that has many advantages over the prior art. A very low profile is provided by the arrangement of the carrier plates and contact legs on substantially the same level. This moreover allows a very short stroke. The simplicity of the construction lends itself to automation in manufacture and low maintenance in use. Any readjustments frequently required in known contact arrangements after assembly are dispensed with by the supporting of the movable parts on corresponding molded pieces.

Although minor modifications might be suggested by those versed in the art, it should be understood that we wish to embody within the scope of the patent warranted hereon all such embodiments as reasonably and properly come within the scope of our contribution to the art.

We claim:

ii. A compact electrical contact arrangement comprising a generally planar single unitary contact spring having a movable free end, said contact spring being slotted at its free end to form adjacent first and second legs, said first leg having a free end bent out of the plane of the contact spring and said second leg having its free end generally in the plane of said contact spring. first and second carrier plates electrically insulated from said contact spring and each having a contact means carrying end, said contact means carrying end of said first carrier plate lying below said first spring leg and said second carrier plate having its contact means carrying end bent out of the plane of said corner plate and lying above said second spring leg portion said contact spring and said carrier plates lying in substantially the same plane.

2. An electrical contact arrangement according to claim 1 wherein said first spring leg has a greater spring force than said second spring leg.

3. A contact arrangement according to claim 1 wherein said contact spring and said carrier plates are anchored in a common body of insulating material. 

1. A compact electrical contact arrangement comprising a generally planar single unitary contact spring having a movable free end, said contact spring being slotted at its free end to form adjacent first and second legs, said first leg having a free end bent out of the plane of the contact spring and said second leg having its free end generally in the plane of said contact spring, first and second carrier plates electrically insulated from said contact spring and each having a contact means carrying end, said contact means carrying end of said first carrier plate lying below said first spring leg and said second carrier plate having its contact means carrying end bent out of the plane of said corner plate and lying above said second spring leg portion said contact spring and said carrier plates lying in substantially the same plane.
 2. An electrical contact arrangement according to claim 1 wherein said first spring leg has a greater spring force than said second spring leg.
 3. A contact arrangement according to claim 1 wherein said contact spring and said carrier plates are anchored in a common body of insulating material.
 4. A low profile electrical contact device comprising a contact spring having a generally planar configuration, said contact spring having a first end bifurcated to provide juxtaposed first and second spring leg portions each connected at one end to said contact spring and each having a free end portion with a contact means thereon, said first leg having its free end portion bent out of the plane of the contact spring, first and second carrier plates electrically insulated from said contact spring and each having a contact means carrying end, said contact means carrying end of said first carrier plate lying below said first spring leg and said second carrier plate having its contact means carrying end lying above said second spring leg portion, an operating member for moving said free ends of said contact spring, said operating member passing below said free end portion of said first leg and above said free end portion of said second leg so that said movement of said operating member moves said spring legs.
 5. An electrical device according to claim 4 wherein said free end portions of said first and second spring legs have laterally projecting portions which are vertically spaced and overlie each other.
 6. An electrical contact device according to claim 4 wherein said operating member is movable by a relay armature in a direction perpendicular to said spring legs.
 7. An electrical contact device according to claim 4 wherein said first spring leg free end portion has a hole therethrough, said operating member having an upstanding projection passing through said hole.
 8. An electrical contact device according to claim 4 wherein said operating member is generally U-shaped having a base portion with arms upstanding from each end thereof, said base portion being gripped by said spring leg portions, said operating member arms having the upper portions thereof projecting through holes in said armature.
 9. An electrical contact device according to claim 8 wherein said armature is of a U-shaped configuration having a base and a pair of arms partially encircling one end of an electromagnetic coil, said armature base portion having holes therein receiving the upper ends of said operating member arms, said armature arms being connected to a spring-biasing means which acts to bias said armature base end upwardly against a stop member so that when said coil is not energized said second spring leg free end portion contacts said bent portion of said second carrier plate and said first spring leg free end portion is not contacting said first carrier plate portion.
 10. An electrical contact device according to claim 9 wherein said coil has a yoke thereabout, said armature base portion being removed a greater distance from a yoke than said armature arm ends when said coil is not energized so that upon energization of said coil said armature base portion is drawn toward said yoke and thereby moves said operating member downwardly to break the contact between said second spring leg portion and said second carrier plate and to make the contact between said first spring leg portion and said first carrier plate. 